Unexpected Mischeif
by FlamingRose11
Summary: Casey has gotten daring. Derek doesn't really know what to do in response. heck! he doesn't even know if the world is still turning! it's better than the summary! read and review please!


**AN: new oneshot i wrote a while back and really couldn't decide whether or not it was worth posting, but I'll just post it and say what the Dickens and let you readers decide! which means you must review so i know your thoughts. hope you enjoy it!**

Derek laid on his bed listening to Kate Perry's _I kissed a girl_ smiling to himself, chuckling under his breath. Even though the song was a bit ridiculous, he, like every boy his age, enjoyed the thought of girl on girl for some weird hormonal reason. It was so ridiculous that he found it amusing. He tapped his foot to the music.

_I kissed a girl and I liked it_

_The taste of her cherry chap stick _

_I kissed a girl just to try it _

_I hope my boyfriend don't mind it _

He closed his eyes and chuckled under his breath once again, a smirk crossing his face.

He heard someone else laughing quietly under their breath. He opened his eyes and turned his attention to the doorway to his room. There was Casey, casually leaning against the doorframe looking at him with a seductive stare. It left chills running up his spine. He tried to keep from blushing. He sat up and looked at her with the most swave nonchalant look he could muster.

"What exactly do you find so funny? I thought Miss Keener had no sense of humor," he said daringly trying to keep from slipping on his defenses. It was obvious to him and everyone else he liked his stepsister, of course he would be mortified if she ever found out.

Casey chuckled. He was always so adorable. Especially when he had that famous smirk across his face. She enjoyed this new daring side of herself she had found in the last couple of days. Well, that she exhibited anyways. She always had a daring side. She barely let it out except every once in a while, but usually on accident. Another thing Derek was good at: letting her get reckless. She was letting her wild side out now and it felt good.

It started when Emily had dared her in chemistry when the teacher had run off to make a lot of copies of some flyers for an academic tournament coming up. The dare was to kiss a guy for no reason. Yeah, it was a slutty kind of thing to do, but her daring curiosity had started overwhelming her. She had always wanted to try something like that anyways, so she did the unthinkable. She told Emily 'pick a guy'.

Emily was nice. She picked Dexter, one of the hottest single boys in school. Before she knew what she was doing, Casey had already pressed her mouth to his. He was definitely caught by surprise, but after a while he got into it. she pulled back and ran to her seat right before the teacher walked in the door. In the middle of chemistry she felt a tap on her shoulder. It was Dexter. She acknowledged his presence and continued taking notes. She felt him lean closer and whisper in her ear, "that was hot." She smiled in spite of herself. "You know you're not my type," she said. Of course he knew. Everyone knew she liked Derek. Everyone except Derek. He chuckled.

"I'm just asking you to set me up with your friend. I would really like to find out if she's as good a kisser as you."

"better," Casey said slyly.

"And how would you know," a joking smile being made evident in his voice.

"That's for me to know and you to find out," she said in a responding joking manner.

"So cliché," he responded. He ended up asking Emily out and everything worked great, but after that day, she was a more free, daring, bold Casey, and she loved it! Now she wanted to see how her stepbrother would react, if at all. She knew the kind of girls Derek went for, and she was absolutely sure that his stepsister was not on the top of his list, but this would be an easy way to say 'guess what? I like you'. There were plenty of ways she could probably screw this up as she did with most guys, but she had to take a risk, she had to give it a try. She was brought back to the present by Derek's comment.

"I'm waiting for an answer princess," he said.

She looked at him from beneath her eyelashes, a smirk crossing her own face.

"Oh, nothing. Just this pointless song. What bets she has never kissed a girl?" She slowly pushed her body from the doorframe making sure every curve was shown off.

"And you have?" Derek said smoothly disbelieving. She shrugged. Derek's mind started reeling. Had his stepsister actually kissed a girl before? Is that was she trying to say? What kind of screwed over world was this?! Still, he couldn't help but find the thought overwhelmingly hot. She could see the wheels turning in his mind. She smiled a knowing smile. She didn't know what it was with guys and girls kissing each other. she didn't really understand why they didn't find it to be just more competition, but if it worked in her favor this time, it was okay with her. She had him right where she wanted him. She walked farther into his room.

"Are you implying- Casey?" he said somewhat stunned. She moved even closer to him.

"It was freshman year. There were all kinds of new things to try, year full of novelties, and it was an all- girls school soooo...." She waggled her eyebrows at him. His eyes grew wide and his cheeks turned red. A devilish smile crossed her face. A deep sensual laugh escaped through her chest as she threw her head back.

"you-you-you actually..." Derek couldn't finish the thought. She kissed a girl? Casey? it was impossible. It was against all laws of nature!

"No," she said indifferently, " I just wanted to see what your reaction would be." She had him by a string. She liked this feeling of power. She wouldn't use him. She liked him too much for that, but this bold suggestive approach was doing wonders for her. She saw the regular color come back to him and saw every one of his muscles relax. God how much she wanted to feel up those muscles. She came back to earth. She had to focus, of course somehow this all felt natural for some reason.

"Why, you look disappointed," she said seductively, coming even closer to him to where she was standing in front of him, "Do I turn you on?" Derek sat a little taller on his bed. what was with the bold and daring Casey? where was all this coming from? This was completely out of the twilight zone. He didn't get it, not that he wasn't enjoying it.

She leaned in closer, her hands on either side of him resting relaxed on top of the bed, her face inches from his. They hadn't even realized the song started to repeat.

"_I'm curious for you, caught my attention," _Casey sang in a quietly deadly voice. She leaned forward and fiercely crashed her lips onto his. Derek was in utter shock, but not for long. He was almost immediately into it. he instinctively wrapped his arm around her waist and brought her closer to him. The kiss got even deeper. She reached up and wrapped her arm around his neck and tangled her fingers into his hair. He impulsively put his other hand up to her face right along her jaw line.

An involuntary moan escaped from her. She felt him smile against her lips. She felt his tongue graze across her lips imploring for entrance. She instantly gave it to him. They leaned back to where Casey's whole body was against his. He felt his way down her back as she felt her way up his ab muscles as she wanted to do for the longest time. They slowly and reluctantly pulled back. Out of breath they sat up slowly, his arm still wrapped around her waist and hers still around his neck. The song went off.

_"I kissed a girl and I liked it," _Derek whispered, giving Casey the smirk she had grown to love. She returned with her own smile of mischief. "Not that I haven't before."

"oh, I know," Casey said, her eyebrows raised, "let us not forget the many times I have caught you making out with one of my friends on that couch I have been forced to eat popcorn on when watching a romantic comedy." Derek chuckled.

" And by the way, yes, you do."

"What?" Casey asked puzzled.

"you do turn me on," he said, resting his head on hers. She chuckled at the remembrance of her question before their make-out session.

"Good to know," she said smiling before leaning in for another kiss. They heard the door slam.

"Casey! Derek! We're home and you better not have been doing anything mischievous!" George yelled from the bottom of the stairs. They quickly jumped away from each other.

"You better be in your rooms doing your homework!" he yelled.

They ran out into the hallway that separated into their two rooms.

"Ah, but they didn't specify what _kind_ of mischief." Derek said lowly causing Casey to giggle. He leaned forward and left her with a kiss before disappearing into his room.

She walked to her computer desk and sat down just as George walked in.

"Working hard?" he asked.

"Yup. Most definitely," she said, smiling to herself.

Derek opened the document that should've had his English paper on it but of course didn't as George walked in.

"You keeping at that English paper?" he asked.

"Dad, of course. As best as I do, and as best as I can," he said. He walked out the door and down the stairs. Derek walked to his doorway and looked out the door as Casey looked out of hers.

"Nice charm," He said.

"You know you like it," she said smiling.

"You should yell at me or throw something or Dad and Nora are going to get suspicious."

"You're right," she said, "De-rek!" she yelled.

"nice touch," he whispered as he followed her into her room.

"Kids! Chill out and do your work!" Nora yelled from downstairs. A smile spread across their faces.

"Okay!' they said simultaneously as Derek quietly kicked the door closed.

"Do we have to chill?" Derek whispered against Casey's cheek.

"hmmmm...no. I think we can keep on 'fighting'," she said with a smirk, "I don't think they'll mind."

Derek leaned in for a kiss.

"well, this had got to be the quietest fighting we've ever done. Well done Casey MacDonald."

"Same to you Derek Venturi," she said as a smile spread across her lips and he kissed her again.


End file.
